The present invention relates generally to punch press type machines used for notching motor laminations, and more particularly, to an apparatus for stamping rotor and stator laminations from a single lamination blank.
Typically, large electric motors include a cylindrical stator core which is comprised of a stack of relatively thin annular laminations, made of a conductive metal, which surrounds an inner rotor core. Slots are stamped radially from the center of the outer lamination and lined up when built up into a stack of laminations. After these laminations are lined up, the stack of laminations are permanently locked together by welding, riveting, cleating or something similar. These slots are then insulated and copper wires are secured inside. Alignment of the lamination slots is critical at this point because misalignment of adjoining laminations and their slots creates a raided edge. This rased edge can cut through the slot insulation, during the insertion of the copper wires, and cause the copper wires to come in contact with the stator core. This will cause a ground fault in the stator assembly. Similarly, slots are stamped radially in an inner lamination. These laminations are built into a stack or rotor core and permanently locked together in a way similar to the outer stack.
Typically, the slots in the laminations are stamped in the stator or outer lamination and separated from a blank lamination. Then the leftover blank has slots stamped in it to produce the rotor or inner lamination. Depending on volume to be produced, these two operations are performed on two different machines with two different operators. With lower volumes, the procedure still requires two operations. The use of two different machines and operators involves a substantial increase in manufacturing time and expense.
An exemplary stator lamination jig system is disclosed in U.S. Pat. No. 5,551,142, the disclosure of which is incorporated herein by reference.
Accordingly, it would be desirable and advantageous to provide an improved slot stamping apparatus to provide a finished inner lamination and a finished outer lamination from a single lamination blank.
In one aspect, a notching apparatus for notching an outer lamination and an inner lamination from a single lamination blank includes a drive arbor for positioning the lamination blank thereon and an indexing mechanism coupled with the drive arbor for consistent indexing of the lamination blank. A punch station is positioned for having the lamination blank move thereby and includes a punch press and a multi-piece punch and die assembly. The multi-piece punch dies assembly includes an outer slot punch portion, an inner slot punch portion and a separator punch portion. The outer slot punch portion, the inner slot punch portion, and the separator punch portion are each positionable in respective punching positions and non-punching positions. A controller is connected for controlling operation of the press, the indexing mechanism and positioning of the outer slot punch portion, the inner slot punch portion and the separator punch portion. During a notching operation the controller effects the following operations: (a) position one of the outer slot punch portion and the inner slot punch portion in its respective punching position and positioning the other of the outer slot punch portion and the inner slot punch portion in its respective non-punching position; (b) rotate the lamination blank past the punch station in a series of indexing steps through a first rotation; (c) repeatedly engage the lamination blank with the multi-piece punch and die assembly as the lamination blank is rotated through the first rotation forming a first pattern of spaced notches in the lamination blank; (d) reverse the punching/non-punching positions of the outer slot punch portion and the inner slot punch portion; (e) rotate the lamination blank past the punch station in a series of indexing steps through a second rotation; (f) repeatedly engage the lamination blank with the multi-piece punch and die assembly as the lamination blank is rotated through the second rotation forming a second pattern of spaced notches in the lamination blank; and (g) position the separator punch portion in the punching position during one of the first rotation and the second rotation for separating the lamination blank into the inner lamination and the outer lamination; and wherein the first pattern of spaced notches is formed in one of the inner lamination and the outer lamination and the second pattern of spaced notches is formed in the other of the inner lamination and the outer lamination. The subject notching apparatus separates the lamination blank into the inner lamination and the outer lamination as the notches are stamped in one of laminations in one rotation and stamps the notches in the other of the laminations in another rotation, also providing improved manufacturing speed and reduced manufacturing cost.